While I don't think they should exist at all and are blatant corruption, that's wildly overstating the level of "discretion" you're likely to receive for a PBA card.

They might get you out of a minor ticket, in the state/area it's from, and that's less likely if you can't articulate why you have it/how you know the officer it was given to to distribute. (to my knowledge, they're only a particularly widespread thing in the NYC metro area, as well).

They're not likely to get you out of a ticket for the kinds of offenses Cannonball Run participants are committing, IMO.